I stopped my 2021 Chrysler Pacifica, placed the transmission knob into park, opened the driver's door, leaving it opened with the engine running, and walked to the rear of the vehicle. I opened the tail gate and removed some boxes, threw the boxes into a dumpster, which was approximately 20 feet away and forward of the vehicle. I then returned to get two additional boxes from the rear of my vehicle. I retrieved the boxes and as I walked from the rear of the vehicle, it started to back up. I dropped the boxes, jumped out of the vehicle's path and tried to get into the driver's seat to stop the vehicle, but was unsuccessful as the vehicle picked up speed and the driver's door caught me and I fell. My vehicle was stopped after hitting a parked car in our church lot. Just a scratch on my vehicle's rear bumper, but frontend damage to the compact car it hit. No one else was in my vehicle. I then drove to get urgent care from cuts and bruises. (FYI - My insurance covers 100% of my care). I have aa service appointment to have the vehicle checked out tomorrow morning at San Antonio CDJ.